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Discussion Starter · #1 ·
Been doing some datalogging for a updated tune after installing S&B intake.
AFR's were very lean high 13's low 14's.

Problem I am having is Bank 1 is leaner than 2.
Does anyone know what can cause this? Can't really get it tuned right.

I installed new o2 sensors to see if one or both were bad. Didn't change anything.

I have attached a small log for viewing. Just the AFR's, Accel. Ped. Pos, RPM's, and speed.

Thanks for any help.
 

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You're normal. A .2 or .3 or so difference is normal. Many have noticed this before. Avg the 2 to determine where you are. Mine is same way. Switching the Sensors side to side prior to buying new ones, will determine if it is a Sensor related issue or not. If numbers stayed the same, then sensors were OK.
 

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Yup as TB said, it's an acceptable difference between the two banks. For peace of mind you could re-check the header bolts and give the exhaust a quick look over for leaks.
 

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Some of it looks normal and then at times under WOT there are some big differences, like 12.3 on one side and 13.2 on the other. Mine fluctuates as much as .6 or .7 sometimes though. I'd say it's probably normal but maybe check your exhaust flanges, ect.
 

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Discussion Starter · #6 ·
Yeah, I wouldn't think too much about it if it was .3 to .6 difference, but .9 at times makes me think something is wrong.
The only place I see a exhaust leak is like 3 feet down stream just before the muffler.
I guess I will have to take the fender liner out and check the nuts at the headers, maybe a new gasket. I reused the old ones.

Randy at Uprev said he couldn't get it tuned right with that much difference between the banks.

Bank 1 is the driver side right?
 

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What's your set up? Are you running cats?
 

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Discussion Starter · #8 ·
What's your set up? Are you running cats?
Setup is, DTLT headers, reso's removed and replaced with MF HFC's, FM Y-pipe, single in - dual out MF muffler. Just installed a S&B intake, prior to that had a K&N drop in. Did some datalogs and found I was way lean and this was before I installed the S&B.

I was looking at a logs from my first tune from Uprev and the AFR's were pretty equal, only a slight difference at times. These were back in Nov. of 09'.
Can't hear or see anything, but I'm starting to think I do have a leak at the headers.
 

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Setup is, DTLT headers, reso's removed and replaced with MF HFC's, FM Y-pipe, single in - dual out MF muffler. Just installed a S&B intake, prior to that had a K&N drop in. Did some datalogs and found I was way lean and this was before I installed the S&B.

I was looking at a logs from my first tune from Uprev and the AFR's were pretty equal, only a slight difference at times. These were back in Nov. of 09'.
Can't hear or see anything, but I'm starting to think I do have a leak at the headers.
Check the entire exhaust. It sounds like it's before the Y pipe based on the AFR difference. Check the welds around the O2 sensors too, sometimes they will leak at the weld. Good luck man! Oh and yes, Bank 1 is the drivers side. Check that side, like now....LOL
 

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Ok you definitely have a light leak before the cats with that much difference, look at the nuts on the headers on bank one, if they are good then look at the welds on your b- pipes before the cats, do it quickly cause that much difference will cause your cat to fail, which happened to me. Also make sure that there is no air leaks, and that the intake tube is securely fastened, cause that will also cause a difference in your readings. Good luck.
 

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Discussion Starter · #11 ·
OK, pulled the wheels and fender liners and checked the headers.
No soot, no loose nuts.
So I swapped the AFR sensors and did some data logging.
This changed things. With them swapped, both banks were in the mid 13's range and fairly equal at WOT up until about 4300 rpm then bank 1 was a little higher, but not much, .3 to .4 difference.
I figured if swapping them changed things, then something is up with the sensors. So I put new ones in.

Randy sent me a updated tune, I will do some more data logs tonight and see where I'm at.
 

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Question about one bank running lean. On my 04 I keep getting the damn p1283 code! I was running NO cats at this time. Thought it was the A/F sensor, replace both of them, clear the self learning memory, and it comes back after a day or so. Replaced my rear o2s, still comes back. So I barrow my brother in laws OTC scan tool to figure out what the hell is going on the my bank 2 A/F sensor is reading lower then my bank 1 A/F sensor. So I replaced my cats/manifolds and used NEW gaskets, checked for leaks before the sensor, no leaks. Checked for intake leaks, absolutely no freakin leaks!

This was the reading before replacing the manifolds/cats



After I replaced my manifolds the A/Fs on both banks seems to even out a little bit but I wasn't able to datalog anything when I had time to work on it. So does anyone have any ideas on what could cause this code on the Titan? I've searched google high and low even on different nissan forums (350z, murano, xterras and stuff) since I figure they would have a similar fix, but still nothing! I checked the cats before I installed them and they looked good. The silly thing is I was able to pass my emissions test, no codes, all my readiness tests passed. I haven't driven it enough to see if the code will go away on its own. I also cleaned the MAF but im thinking about swapping it out with another one to see if that might fix it?

Please any ideas? Even though I don't need emissions for another year i'd love to have that light turn off!


ALSO- After I installed my new manifolds the engine would start just fine when cold, but when warmed up it would start and die! I would have to rev it up while starting it to be able to let it idle, it was like this for probably 2 days and now its normal again, I also noticed when I did this the idle was at about 550-575 in PARK. Could it be my fuel pump going out? Anyone have this problem before? Fuel pump going out causing my p1283 lean code by loss of fuel pressure?



Beginning of the video the truck is running, then shut off, restarted to show how it starts/dies, then shutoff again, then started while pressing on the pedal a tad.
 
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